|Publication number||US6487347 B2|
|Application number||US 09/217,527|
|Publication date||Nov 26, 2002|
|Filing date||Dec 21, 1998|
|Priority date||Mar 24, 1997|
|Also published as||CA2292185A1, EP1014135A1, US20020001443|
|Publication number||09217527, 217527, US 6487347 B2, US 6487347B2, US-B2-6487347, US6487347 B2, US6487347B2|
|Inventors||Anne G. Bringuier|
|Original Assignee||Corning Cable Systems Llc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (15), Non-Patent Citations (9), Referenced by (27), Classifications (10), Legal Events (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention is a Continuation-in-Part of U.S. Ser. No. 08/823,260, now U.S. Pat. No. 5,852,698 filed Mar. 24, 1997 the entirety of which is incorporated by reference herein.
This invention relates to optical fiber cables which are suitable for use within building vertical shafts and also are provided with protection against moisture internal migration. In particular, this invention relates to single-tube design optical fiber cables suitable for such uses.
Drop cables are outdoor cables which bring telephone service to buildings, whereas riser cables provide telephone service within buildings. Riser cables extend upwards from basement vaults to wiring closets located on upper floors.
Drop cables must be able to withstand the changing conditions found in the outdoor environment. Most materials increase in length and volume with increases in temperature and decrease in length and volume with decreases in temperature. Each material may have a different rate of change of length given a specified change in temperature. Such a rate is called the coefficient of thermal expansion for a material. Because different materials in a cable may have different coefficients of thermal expansion, temperature changes may induce strains in the cable components. For this reason, changes in optical fiber attenuation over different temperatures are measured in cables intended for outdoor use. Successful cables must not experience unacceptable increases in optical fiber attenuation caused by cable strains induced by temperature-related conditions.
Drop cables also must be protected against migration of moisture within the cable. Although cable jackets are intended to prevent the ingress of water into the cable, no plastic material perfectly stops the ingress of moisture. Furthermore, water may enter a cable at points where the cable jacket has been damaged, or at the end of the cable. Therefore, longitudinal movement of water along the inside of the cable must be prevented. For this reason, water-blocking or water-absorptive material is provided in cable interstices which otherwise could act as conduits for moisture internal migration. Types of materials which may be used for this purpose are gel-like filling and flooding compounds. Filling compounds are disposed alongside the optical fibers within buffer tubes, while flooding compounds are disposed in spaces between the cable jacket and the buffer tubes holding the optical fibers. Many filling and flooding compounds are oil or grease-based. As a result, most filling and flooding compounds provide fuel for combustion. However, most cables intended for outdoor use are not required to be flame-retardant.
Other types of materials are becoming more widely used in outdoor use cables for protection against cable moisture migration. Examples include water-absorptive polymers, which may be inserted into a cable as loose powders or incorporated into tapes which are wrapped about other cable components. Another example is water blocking strength members, as disclosed in U.S. Pat. No. 4,913,517 and 5,389,442.
Cables intended for use within buildings normally are not exposed to the moisture and extreme temperature conditions experienced by cables intended for outdoor use. However, building cables are required by the National Electrical Code to meet criteria indicating that the cables will not act to spread fires within a building. The most well-known test standard for riser-rated cables is Underwriters Laboratories (UL) Standard 1666, “Test for flame propagation height of electrical and Optical-fiber Cables installed vertically in Shafts” (Second Edition, Jan. 22, 1991). The second edition of this standard is referred to herein as UL Standard 1666.
An optical fiber service cable designed to be suitable for both indoor and outdoor use is disclosed in U.S. Pat. No. 5,566,266, which issued on Oct. 15, 1996 in the names of Navé and McDowell. However, the disclosed cable is designed for use with a rather high optical fiber count and discloses an inner tube which itself has an outer diameter of 10.2 mm. Such a cable could not be connectorized using standard buffer tube fanout kits. The cable also employs a tape formed from materials such as a polyimide. Such tapes significantly add to the cost of the cable, and it is necessary to process and splice such tapes.
It is therefore an object of the present invention to provide riser-rated cables having a small diameter and low minimum bend radius which also is formed using low-cost materials.
These and other objects are provided, according to the present invention, by fiber optic cables suitable for both outdoor and indoor applications, comprising: a core tube having an OD of about 3.0 mm or more surrounding a plurality of coated optical fibers; a jacket formed of UV-resistant flame-retardant polymer material surrounding said core tube; and at least one layer of strength members disposed between said core tube and said jacket. The jacket can have an OD of about seven mm or more. The coated optical fibers can experience a short-term increase in signal attenuation of no more than about 0.01 dB when the cable is looped in a radius of 5 centimeters. The strength members can be wrapped around the core tube in opposite directions and the set of two strength member layers can be disposed between and directly contiguous to said core tube and said jacket. The cable is capable of meeting the flame retardance requirements set out in UL Standard 1666 in the absence of a flame-resistant tape. The strength members may be impregnated with a water blocking material.
The present invention embodiments of the invention are described in the several drawings, in which:
FIG. 1 is a cut-back perspective view of a cable according to a first embodiment; and,
FIG. 2 is a cross-sectional view of the cable of FIG. 1.
FIG. 3 is a cross-sectional view of a fiber optic cable according to the present invention.
The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which one or more embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the disclosure will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. The drawings are not necessarily drawn to scale but are configured to clearly illustrate the invention.
A cable 10 according to a first embodiment of the present invention is shown in FIGS. 1 and 2. Cable 10 is designed to include from two to twelve coated and colored 250 μm optical fibers 11. Optical fibers 11 may be either single-mode or multimode fibers, or a mixture of single-mode and multimode fibers. Core tube 12 also may contain a filling compound 17 disposed in the space within the core tube not occupied by the optical fibers. The optical fibers 11 typically are not stranded with each other, and have a length which is from 0% to 0.2% greater than the length of core tube 12. Core tube 12 itself may be formed from a flexible plastic material such as polypropylene (PP). Core tube 12 need not be formed from flame-retardant material.
According to a first embodiment of the present invention (FIGS. 1-2), core tube 12 may have an inner diameter of about 1.8 mm and an outer diameter of about 3.0 mm, and loosely contains the optical fibers 11. Buffer tubes having an outer diameter of about 3.0 mm are widely used, so that the buffer tube may be connectorized using equipment which is already available to the industry. Core tube 12 may have an OD greater than about 3.0 mm.
An inside layer 13 and an outside layer 14 of flexible strength members are stranded in opposite directions about core tube 12. In a cable according to the first embodiment, eight yarns form outside layer 14 and six yarns form inside layer 13. Inside strength member layer 13 is contiguous to core tube 12; outside strength member layer 14 is directly contiguous to inside strength member layer 13; and jacket 16 is directly contiguous to outside strength member layer 13. A polyester ripcord 15 lies at the inner surface of jacket 16.
The strength members forming layers 13 and 14 are chosen to be highly flexible. For example, the strength members forming layers 13 and 14 can be Advantex or Aquablok reinforcements, available from Owens Corning, which are fiberglass yarns including a superabsorbent polymer, or flexible rovings from NEPTCO including a water blocking substance thereon. The reinforcements swell up to five times their own weight in deionized water, providing effective water-blocking protection to the space between jacket 16 and buffer tube 12.
These strength members are chosen to provide sufficient anti-buckling and tensile strength to the cable. The exemplary reinforcements have a tensile modulus of elasticity of 7×104 MPa, allowing the cables according to the present invention to have, for example, a maximum tensile loading during installation of 1320 N, and a long term maximum tensile load of 330 N.
The outer jacket 16 may be formed from polyvinyl chloride material which is both ultraviolet resistant and flame retardant, adapting the cables according to the present invention for both indoor and outdoor use. According to the first embodiment of the invention, the average outer diameter of the outer jacket 16 may be about 7.0 mm or less.
A sample cable according to the first embodiment of the present invention having a length of 20 m containing three multimode fibers and nine single-mode fibers was tested for optical fiber attenuation at low bend radius. The cable excess fiber length percentage was 0.2%. The single-mode fibers were concatenated and terminated separately from the multimode fibers. Attenuation test sets operating at 1300 nm for multimode fibers and 1550 nm for single-mode fibers were connected to the concatenated fibers. The cable sample was placed in a loop using a template with a possible radii range of 8 cm to 2 cm. The loop diameter was slowly decreased from 8 cm down to 2 cm while the optical attenuation (Δ dB) was measured. Table 1 sets out the results. (Results at 2 cm are not reproduced, as the optical fiber itself has a minimum bend radius of about 2.5 cm for long-term mechanical reliability). Due to the nature of the test, single-mode values are to be divided by nine, and multimode values are to be divided by 3 to obtain average values for individual optical fibers.
Change in attenuation (Δ dB) in concatenated
optical fibers at different cable bend radii; results given
separately for single-mode (SM) and multimode (MM)
Trial 1 SM
Trial 1 MM
Trial 2 SM
Trial 2 MM
Trial 3 SM
Trial 3 MM
When the proper division is made, it is seen that both the single-mode and the multimode individual optical fibers had a change of signal attenuation of 0.01 dB or less at a cable bend radius of 5 cm. Furthermore, the cable did not kink even at a bend radius of 2 cm.
Cables according to the present invention perform very well during stripping, handling, and bending. Because of the small outside diameter and flexibility of the cable, a ring cut is difficult to make in the jacket using a hook blade. Use of a straight blade for this purpose therefore is recommended.
Cables according to the present invention may be used in interbuilding and intrabuilding backbones in aerial, duct, or riser applications. These cables have a specified operating temperature of −40° C. to +70° C. These cables are UL 1666 listed and meet the requirements of ICEA-596.
The cable core comprising tube 12, filling compound 17 and coated optical fibers 11 may be made using either a vertical or horizontal buffering line as known to the prior art. Spinners may be used to apply strength reinforcement member layers 13 and 14. The tension applied to the strength members may be 350 g, and their lay length may be 250 mm. In jacketing cables according to the first embodiment of the present invention, a tip diameter of 5.25 mm and a die diameter of 7.0 mm may be used. Six inches may separate the die orifice and a cooling water vat, and the extruder temperature profile used in forming the outer jacket may cover the range 142-1850° C. A line speed of 25 m/min. may be employed. Aramid fiber yarns coated with a swellable powder or film are alternative strength members which may be used. A flame-retardant polyethylene material may be used as a jacket material for zero halogen, low smoke applications.
Core tubes having an OD greater than 3.0 mm can be used in cables of the present invention (FIG. 3). For example, the present invention may be practiced in the form of a fiber optic cable 20 with bundled optical fibers 11 disposed in a core tube 22 formed of, e.g., PP that may have a filling compound 17 or a dry water swellable compound therein for blocking the flow of water. The OD of core tube 22 may be in the range of about 3.0 mm to about 6.0 mm or more. Fiber optic cable 20 can include one or more layers of strength members 13,14 as in the embodiment of FIGS. 1-2, for example, eight yarns form outside layer 14 and six yarns form inside layer 13. Inside strength member layer 13 is generally contiguous to core tube 12; outside strength member layer 14 is generally contiguous to inside strength member layer 13; and jacket 16 is generally contiguous to outside strength member layer 13. Fiber optic cable 20 can include a jacket 26 with one or more ripcords 15. Since the OD of core tube 12 can be in the range of about 3.0 mm to about 6.0 mm or more, the OD of jacket 26 can be, for example, about 7.0 mm or less to about 12 mm or more.
It is to be understood that the invention is not limited to the exact details of the construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art without departing from the scope of the invention.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4892382||Sep 26, 1988||Jan 9, 1990||Siecor Corporation||Dielectric optical drop cable|
|US4893893||Feb 8, 1988||Jan 16, 1990||American Telephone And Telegraph Co., At&T Bell Laboratories||Strengthened buffered optical fiber|
|US4913517||Jul 11, 1988||Apr 3, 1990||American Telephone And Telegraph Company, At&T Bell Laboratories||Communication cable having water blocking strength members|
|US5148509||Mar 25, 1991||Sep 15, 1992||Corning Incorporated||Composite buffer optical fiber cables|
|US5208889||Oct 24, 1991||May 4, 1993||W. L. Gore & Associates, Inc.||Optical fiber ribbon cable and assembly thereof with a connector|
|US5389442||Nov 25, 1992||Feb 14, 1995||At&T Corp.||Water blocking strength members|
|US5566266||Jan 26, 1995||Oct 15, 1996||Siecor Corporation||Optical fiber service cable|
|US5574816||Jan 24, 1995||Nov 12, 1996||Alcatel Na Cable Sytems, Inc.||Polypropylene-polyethylene copolymer buffer tubes for optical fiber cables and method for making the same|
|US5740295 *||Nov 2, 1994||Apr 14, 1998||Lucent Technologies Inc.||Low fiber count optical cable|
|US5748823||Jan 30, 1997||May 5, 1998||Siecor Corporation||Single-tube plenum ribbon cable|
|US5822485 *||Jan 13, 1997||Oct 13, 1998||Siecor Corporation||Optical cable containing parallel flexible strength members and method|
|US5852698 *||Mar 24, 1997||Dec 22, 1998||Siecor Corporation||Riser-rated optical cable|
|EP0349206B1||Jun 23, 1989||Sep 15, 1999||AT&T Corp.||Bonded array of transmission media|
|EP0762171A1||Jul 23, 1996||Mar 12, 1997||AT&T Corp.||Sub-miniature optical fiber cables, and apparatuses and methods for making the sub-miniature optical fiber cables|
|JPH01245205A||Title not available|
|1||Berk-Tek Product Literature; Berk-Tek UNI-Lite Optical Fiber Cable Riser Outside Plant Series. Revision Date: Mar. 10, 1995.|
|2||BICC Brand-Rex Cable Samples, Fall, 1997.|
|3||IBM Technical Disclosure Bulletin; vol. 39, No. 01; Jan. 1996.|
|4||IWCS Proceedings 1996, Development of a Riser Rated Indoor/Outdoor Loose Tube Fiber Optic Cable; Scott M. Chastain and James W. Thornton; pp. 369-373.|
|5||LightWave Magazine, Oct. 1997, p. 22.|
|6||Lucent Technologies Product Literature, CampusMax(TM) Outside Plant Cables; 5024FS NAK May, 1996.|
|7||Lucent Technologies Product Literature, CampusMax™ Outside Plant Cables; 5024FS NAK May, 1996.|
|8||Singlemode, General Purpose OSP Cable AccuRibbon Core, Dielectric Sheath High Fiber Count AccuRibbon OSP Cable-RFX; Lucent Technologies, Fiber Optic Products, Jun. 1997; 2A-47.|
|9||Singlemode, General Purpose OSP Cable AccuRibbon Core, Dielectric Sheath High Fiber Count AccuRibbon OSP Cable—RFX; Lucent Technologies, Fiber Optic Products, Jun. 1997; 2A-47.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7035513||Mar 25, 2004||Apr 25, 2006||Corning Cable Systems Llc||Fiber optic drop cables suitable for outdoor fiber to the subscriber applications|
|US7050688||Jul 18, 2003||May 23, 2006||Corning Cable Systems Llc||Fiber optic articles, assemblies, and cables having optical waveguides|
|US7079734||Dec 22, 2004||Jul 18, 2006||Corning Cable Systems Llc||Fiber optic drop cables suitable for fiber to the subscriber applications|
|US7184634||Apr 6, 2005||Feb 27, 2007||Corning Cable Systems, Llc.||Fiber optic drop cables suitable for outdoor fiber to the subscriber applications|
|US7206482||Apr 6, 2005||Apr 17, 2007||Corning Cable Systems, Llc.||Protective casings for optical fibers|
|US7447406||May 26, 2006||Nov 4, 2008||Prysmian Cables & Systems Limited||Coated optical fibre unit and methods of manufacturing coated optical fibre units|
|US8224140 *||Dec 11, 2009||Jul 17, 2012||Corning Cable Systems Llc||Cables with bend insensitive optical fibers|
|US8335417||Sep 23, 2010||Dec 18, 2012||Corning Cable Systems Llc||Crush-resistant fiber optic cables employing bend-resistant multimode fibers|
|US8488929||Oct 14, 2010||Jul 16, 2013||Corning Cable Systems Llc||Tactical cable|
|US8588567||Apr 13, 2012||Nov 19, 2013||Ccs Technology, Inc.||Optical cable and method for producing an optical cable|
|US8705921||Jul 27, 2012||Apr 22, 2014||Corning Cable Systems Llc||Fiber optic drop cable|
|US8737789||Jun 13, 2013||May 27, 2014||Corning Cable Systems Llc||Tactical cable|
|US8965158||Sep 16, 2013||Feb 24, 2015||Corning Cable Systems Llc||Crush-resistant fiber optic cable|
|US9075215||Aug 11, 2011||Jul 7, 2015||Corning Cable Systems Llc||Duplex cables and zipcord cables and breakout cables incorporating duplex cables|
|US9482838||Feb 20, 2015||Nov 1, 2016||Ccs Technology, Inc.||Crush-resistant fiber optic cable|
|US9669592||Mar 12, 2014||Jun 6, 2017||Corning Optical Communications LLC||Method of manufacturing a fiber optic drop cable|
|US20050169588 *||Mar 13, 2003||Aug 4, 2005||Ralph Sutehall||Coated optical fibre unit and methods of manufacturing coated optical fibre units|
|US20050213899 *||Apr 6, 2005||Sep 29, 2005||Hurley William C||Fiber optic drop cables suitable for outdoor fiber to the subscriber applications|
|US20050213900 *||Apr 6, 2005||Sep 29, 2005||Rhyne Todd R||Protective casings for optical fibers|
|US20050213903 *||Mar 25, 2004||Sep 29, 2005||Mohler James D||Fiber optic drop cables suitable for outdoor fiber to the subscriber applications|
|US20050281517 *||Jun 18, 2004||Dec 22, 2005||Wessels Robert A Jr||Multi-layered buffer tube for optical fiber cable|
|US20060133748 *||Dec 22, 2004||Jun 22, 2006||Seddon David A||Fiber optic drop cables suitable for fiber to the subscriber applications|
|US20070063363 *||May 26, 2006||Mar 22, 2007||Pirelli General Plc||Coated optical fibre unit and methods of manufacturing coated optical fibre units|
|US20090087148 *||Jan 18, 2008||Apr 2, 2009||Bradley Kelvin B||Optical fiber cables|
|US20110075977 *||Sep 23, 2010||Mar 31, 2011||Register Iii James A||Crush-Resistant Fiber Optic Cables Employing Bend-Resistant Multimode Fibers|
|US20110110634 *||Oct 14, 2010||May 12, 2011||Hurley William C||Tactical Cable|
|US20110142403 *||Dec 11, 2009||Jun 16, 2011||Hurley William C||Cables with Bend Insensitive Optical Fibers|
|Cooperative Classification||G02B6/441, G02B6/4494, G02B6/4436, G02B6/443|
|European Classification||G02B6/44C11, G02B6/44C5, G02B6/44C7F, G02B6/44C7A|
|Dec 21, 1998||AS||Assignment|
Owner name: SIECOR OPERATIONS, LLC, NORTH CAROLINA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BRINGUIER, ANNE G.;REEL/FRAME:009672/0128
Effective date: 19981221
|May 22, 2006||FPAY||Fee payment|
Year of fee payment: 4
|May 17, 2010||FPAY||Fee payment|
Year of fee payment: 8
|Apr 28, 2014||FPAY||Fee payment|
Year of fee payment: 12
|Aug 18, 2014||AS||Assignment|
Owner name: CORNING CABLE SYSTEMS LLC, NORTH CAROLINA
Free format text: CHANGE OF NAME;ASSIGNOR:SIECOR OPERATIONS, LLC;REEL/FRAME:033553/0041
Effective date: 20000524
|Aug 25, 2014||AS||Assignment|
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CORNING CABLE SYSTEMS LLC;REEL/FRAME:033600/0033
Effective date: 20030124
Owner name: CCS TECHNOLOGY, INC., DELAWARE